Despite iOS usage hitting an all time high, sales of Apple’s iPhone have declined over the past few months as customers await the arrival of the company’s next-generation iPhone. Rivals of the Cupertino-based company, on the other hand, have released a slew of new handsets and have achieved increased sales. While the iPhone 4S remained the most popular smartphone in the United Kingdom, sales fell from nearly a quarter of all handsets sold in March to about a fifth of all handsets sold in June, the Financial Times reported. Sales of Samsung’s flagship Galaxy S III smartphone have also impacted the iPhone — according to market research firm Gfk, the device captured nearly 18% of the market in its first week in June.